St Edward State Park
My high school is now one of the best parks anywhere: St. Edward State Park. Toward the northerly end of the east side of Lake Washington, a pious logger donated a big hunk of land to the Seattle Archdiocese, which built what was intended to be the start of a huge religious complex. I went there as a high school seminary student.
Between one thing and another, the Archdiocese decided it was best to sell off the land, but wisely put conditions on its use. Thus it is the biggest vaguely-natural area still on Lake Washington. When the park system (running low on money) looked into privatizing the park, local citizens did great work to come up with alternatives. See Citizens for St Edward State Park: http://www.c4sep.org/
Take a photo tour: http://picasaweb.google.com/rewinn/Steds